The subject matter disclosed herein relates generally to optical scanning, and more particularly to laser scanners.
Laser scanners, such as the FARO Photon 120, are typically used for scanning closed or open spaces like interior spaces of buildings, industrial installations, and tunnels. Laser scanners are used for many purposes, including industrial applications and accident reconstruction applications. A laser scanner can be used to optically scan and measure objects in a volume around the laser scanner. Laser scanners collect a variety of data points representing objects in the surrounding volume. Such data points are obtained by transmitting a beam of light onto the objects in the volume and collecting the reflected or scattered light to determine, for each point, a distance, two angles (for example, an azimuth and a zenith angle), and a gray-scale value (i.e., a quantity related to the irradiance of the scattered light returned to the scanner). This raw scan data is collected, stored and sent to a processor or processors to generate a scanner image that represents the objects measured in the three dimensional (3D) volume surrounding the scanner, the scanner image being displayed on a monitor or similar device. In order to generate the scanner image, at least four values are collected for each data point. These four values may be the distance, two angles, and gray-scale value, as described above, or they may be transformed values such as the x, y, and z coordinates, in addition to the gray-scale value.
Many contemporary laser scanners also include a camera mounted on the laser scanner for gathering camera digital images of the environment and for presenting the camera digital images to an operator of the laser scanner. By viewing the camera images, the operator of the scanner can determine the field of view of the measured volume and adjust settings on the laser scanner to measure over a larger or smaller region of space if the field of view needs adjusting. In addition, the camera digital images may be transmitted to a processor to add color to the scanner image. In order to generate a color scanner image, at least six values (three positional coordinates such as x, y, z; and red value, green value, blue value or “RGB”) are collected for each data point.
One drawback to relying on a camera digital image for determining that the correct data has been gathered by the laser scanner is that the process of taking pictures with the digital camera is separate from the process of collecting scan data. The digital image may correctly represent the image, even if the scan data contains an error or is not complete.
This shortcoming may be eliminated through the use of an external computer such as a laptop computer, for example. However, in many situations, it is inconvenient to carry a computer in addition to a scanner and a tripod to a location of interest. An example of such a situation, described in more detail hereinbelow, is a crime scene in which a laser scanner is used for forensic analysis.
Accordingly, and while existing laser scanners may be suitable for their intended purpose, there remains a need in the art for laser scanners that overcome these drawbacks.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.